1. Field of the Invention
The present invention relates generally to a mobile communication system, and more particularly to a paging system and method for use in mobile communication system providing an MBMS (Multimedia Broadcast/Multicast Service).
2. Description of the Related Art
With the increasing development of communication technologies, a conventional CDMA (Code Division Multiplex Access) mobile communication system has rapidly evolved to a multicast multimedia communication system capable of transferring a large amount of data, e.g., voice data, packet data, and a circuit data. As a result, a Broadcast/Multicast Service system capable of multicasting a service from a single data source to a plurality of UEs (User Equipments) to support multicast multimedia communication has been developed. The Broadcast/Multicast Service is classified into a CBS (Cell Broadcast Service) functioning as a message-based service and an MBMS (Multimedia Broadcast/Multicast Service) for providing multimedia data, e.g., real-time video and audio data, still images, text, etc.
FIG. 1 is a block diagram illustrating a network configuration for providing the MBMS service in a mobile communication system. Referring to FIG. 1, the network system for providing the MBMS service includes a UE 101 for receiving the MBMS service, a UTRAN (Universal Mobile Telecommunications System (UMTS) Radio Access Network) 102, an SGSN (Serving General Packet Radio Service (GPRS) Support Node) 103 included in a CN (Core Network), an HLR (Home Location Register) 104, a GGSN (Gateway GPRS Support Node) 105, a BM-SC (Broadcast/Multicast-service Center) 106.
The UE 101 is connected to the UTRAN 102 to perform a call control process, supports both CS (Circuit Service) and PS (Packet Service), and includes hardware and software modules for receiving the MBMS data. The UTRAN 102 includes a Node B (not shown), and an RNC (Radio Network Controller) (not shown). The UTRAN 102 performs a protocol conversion process, such that it can transmit RF (Radio Frequency) data or control messages having been received from the UE 101 via an air interface to the CN using a GTP (GPRS Tunneling Protocol). In this case, the GPRS is a packet data service performed in the UMTS network. The SGSN 103 is a network node for managing subscriber and position information of the UE 101. The SGSN 103 is connected to the HLR 104, such that it can manage the subscriber and position information.
The HLR 104 stores subscriber information of a packet domain and routing information. It should be noted that the HLR 104 can also be included in another PLMN (Public Land Mobile Network) because of the roaming capability of the UE 101. The GGSN 105 is a termination end of the GTP in the UMTS network, such that it can interwork with the Internet, a PDN (Packet Domain Network) or other PLMNs, etc. The GGSN 105 is connected to the BM-SC 106, The GGSN 105 receives MBMS streams from the BM-SC 106, and transmits the received MBMS streams to the SGSN 103. The SGSN 103 is included in the CN, and connects the UTRAN 102 to the CN. The SGSN 103, having received the MBMS streams from the GGSN 105, controls MBMS-associated services of subscribers, i.e., UEs, who wish to receive the MBMS. In order to control the MBMS-associated services, the SGSN 103 manages data associated with individual MBMS service charges, and selectively transmits MBMS service data to a specific RNC. The SGSN 103 configures/manages an SGSN service context in association with the MBMS service, and re-transmits the MBMS streams to the RNC. The service context used for the MBMS is called an MBMS context, which indicates the set of control information elements needed to provide a prescribed MBMS. The RNC controls a plurality of Node Bs, selects a specific Node B where a UE requesting the MBMS exists from its own Node Bs, and transmits MBMS data to the selected Node B. Additionally, the RNC controls a radio channel established to provide the MBMS, configures an RNC service context associated with the MBMS upon receiving the MBMS streams from the SGSN 103, and manages the configured RNC service context.
The RNC and the SGSN 103 manage service-associated information for every MBMS, and define the service-associated information managed for every MBMS as the MBMS context. In this case, there is a variety of information in the MBMS context, for example, name information, i.e., IDs, of UEs requesting the MBMS, information indicative of a service area where the UEs exist, and QoS information needed to provide the MBMS.
Basic information associated with the MBMS must be transmitted to UEs in order to provide the UEs with a prescribed MBMS. If the UEs, having received the basic information associated with the MBMS, wish to receive the prescribed MBMS, name information of the UEs must be transmitted to the network. Upon receipt of the name information of the UEs requesting the prescribed MBMS, the network must call or page the UEs and then establish a radio bearer used for providing the MBMS. If the radio bearer has been established with the UEs, the prescribed MBMS can be provided to the UEs via the setup radio bearer. However, if the MBMS is terminated, this MBMS termination state must be recognized by all the UEs, and all the UEs must release all resources having been allocated to implement the MBMS, such that a normal MBMS is made available.
In this case, a transmission scheme for transmitting the MBMS is determined to be either a PTP (Point to Point) scheme or a PTM (Point to Multipoint) scheme. The PTP scheme transmits MBMS data desired by individual UEs over a dedicated channel. The PTM scheme provides the same MBMS data to the UEs over a common channel.
A method for transmitting MBMS control information, i.e., information of a channel over which the MBMS data will be transmitted, to UEs requesting the MBMS is differently applied to a PTP-based MBMS and a PTM-based MBMS. In this case, the channel information includes logical channel information, transport channel information, physical channel information, etc. More specifically, in providing the MBMS according to the PTP scheme, all the UEs to which the MBMS data will be transmitted receive the MBMS data over different channels. The RNC assigns a DCCH (Dedicated Control CHannel) to individual UEs, and transmits control information of a channel over which the MBMS data will be transmitted over the DCCH. Therefore, an RRC (Radio Resource Control) connection is required to transmit the MBMS control information over the DCCH.
Alternatively, in providing the MBMS data according to the PTM scheme, all the UEs to which the MBMS data will be transmitted receive the MBMS data using one or more channels in common. In the PTM scheme, there is no need to separately receive a variety of channel information associated with the MBMS. That is, the PTM scheme enables the UEs requesting the MBMS data to receive the MBMS channel information over a common control channel denoted as an MCCH (MBMS Control CHannel). In receiving the MBMS channel information over the MCCH, there is no need for the UEs to establish the RRC connection. That is, if the UEs can receive the MBMS channel information over the MCCH, system complexity is greatly reduced and wireless resources are effectively used.
Accordingly, a call control procedure for transmitting and receiving the MBMS control messages in the case of using a predetermined MBMS is needed. Additionally, there is a need for a call control procedure for transmitting MBMS data using the PTP and PTM schemes in consideration of the number of UEs requesting the MBMS.